One aspect of the production of steel is the manufacture of long steel sheets. Traditionally these steel sheets are cut into long flats or wound into large coils weighing several tons. Prior to cutting and shaping into finished products, these steel sheets must be transported from the mills where they are produced to the manufacturing plants where they are processed. During at least a portion of this journey the steel is typically hauled using a truck tractor and trailer.
The shipping of steel and other metal coils by truck trailer presents several problems. In addition to weight and trailer load capacity considerations, particular attention must be paid to securing metal coils to the trailer to prevent shifting of the load during transport. This problem is particularly challenging for a coil weighing several tons and traveling at highway speeds. As coils by their very nature have rounded surfaces, they raise the additional hazard of rolling into traffic should they become unsecured from a moving trailer.
Traditionally metal coils 22 have been secured to trailers 20 using a series of chains 24 and wooden blocks 26 arranged to prevent the coil from rolling. One such arrangement is shown in FIG. 1. In this particular arrangement, the axis of coil 22 is transverse to the direction of travel. Alternatively, the coil may be arranged on the trailer with the axis of the coil parallel to the direction of travel. Even if a coil is securely restrained on a trailer, particular care must be exercised to insure the coil is prevented from rocking on its rounded surface to prevent the build up of momentum in the multi-ton coil which might overtax the securing chains. In the event of chain failure in a traditional securing configuration, however, the coil is free to roll off of the trailer and onto the road or onto the tractor cab. Also, as coils have a high center of gravity relative to the trailer, large coils are capable of overturning a tractor and trailer without separating from the trailer during emergency maneuvers.